Belt drives are typically utilized to transmit power in outdoor power equipment such as rotary tillers. A typical belt drive will be provided with an idler pulley which holds the belt taut during driving, but which may be released to permit the belt to become slack and disengage it from the pulley. The slacked belt may become so loose as to become disengaged completely from the pulley and thus lose its capacity to re-engage therewith when the idler pulley is tightened. Moreover, the slacked belt may expand where it is looped about the pulley to shorten its scope and inadvertently re-engage therewith in the declutched mode.